The present invention relates generally to mechanisms providing for the transmission of power and electrical signals between a stationary structure and a rotating structure.
There has long been difficulty in transmitting power and electrical signals between a stationary object and a rotating structure. A well-known structure for accomplishing this is a “slip ring”. Typically, a slip ring includes a metal contact, referred to as a brush, which rubs on the circumferential or radial surface of a rotating metal ring. As the metal ring rotates, an electrical current is conducted through the stationary brush. If more than one electric circuit is required, additional ring and brush assemblies are coaxially positioned and stacked to rub against the radial surface or against the circumferential surface. Either the brush or the ring may be stationary.
Unfortunately slip rings suffer from several disadvantages. A slip ring's brush works by a wiping action wherein a brush's contact finger directly abuts against an opposing terminal as the contact surface rotates. The wiping action can create wear on both the finger and contact surface. Excessive wear results in the need to readjust the finger or its contact surface to compensate for the wear and ensure a proper electrical contact. Similarly, the excessive wear can cause debris which contaminates the area of the brush contact. The debris may cause electrical shorts, jam sensitive mechanical movements, and require excessive preventative maintenance.
Furthermore, typically the finger of the brush contact is formed so as to operate in only one direction of rotation. However, rotating platforms sometimes jam or otherwise require attention. In such situations, it is often desirable to rotate the platform in a direction opposite its normal mode of operation. Such manipulation may help to unjam the machine, but the reverse rotation can bend and destroy traditional brush contacts. The damaged contact then needs to be replaced or repaired before the rotating platform can again function properly.
More recently, roll rings have been developed to overcome some of the disadvantages of slip rings for transmitting electrical signals and power from a stationary object to a rotating object. Instead of brushes, the electrical contact incorporates wheels, spheres, or roller bearings which roll so as to reduce wear and friction. However, in order to maintain the wheels or roller bearings in proper space and orientation, a mechanical assembly must be employed to maintain the wheels or roller bearings in proper position and alignment. Unfortunately, this mechanical assembly to position the wheels or roller bearings introduces unwanted weight and cost, and inhibits scalability.
Thus, it would be desirable to provide a circuit assembly for transmitting electricity between a non-rotating structure and a rotating structure that is not subject to the wear and friction of metal brushes.
Moreover, it would be desirable to provide a circuit assembly for transmitting electricity between a non-rotating object and a rotating object that does not introduce unwanted weight and cost, or inhibit scalability.